Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder manifested by a spectrum of behavioral anomalies characterized by impaired social interaction and communication, often accompanied by repetitive and stereotypical behavior. The characteristic impairments can be accompanied by mental retardation and/or epilepsy. The condition becomes apparent within the first three years of life and persists into adulthood.
Early behavioral signs of ASD include avoidance of social interaction, lack of eye contact, failure to develop normal conversational skills, and poor language capacities. In a majority of cases, there is no normal period in the child's development (classic autism). Usually, social development is markedly delayed, and language fails to appear or progress normally. Often, these individuals exhibit personality traits that are characterized as “hyper-literal” with a notable pre-disposition to focus on detail at the expense of abstract meaning.
These characteristics often vary from individual to individual, and, therefore, autism is diagnosed by subjective and behavioral observations. Furthermore, a behavioral-based diagnosis that relies on language and social skills often occurs relatively late in the developmental cycle. Thus, a standardized, neurophysical, diagnostic tool available at early stages of development can facilitate the initiation of therapies at a critical point in time.
It is estimated that one out of every 150 people are affected with ASD, depending on the diagnostic criteria used. The male to female ratio is about four to one. There has been an approximate five-fold increase in the last 10 years in new cases of ASD in the pediatric population of children aged one and a half to six years. These statistics do not reflect the major increase in newly diagnosed cases prior to 1994 when the diagnostic criteria changed.
Although the cause of autism is unknown, recent studies suggest a genetic predisposition to autism associated with disruption of early fetal brain development. There are numerous hypotheses regarding the etiology and pathology of ASD, including a suggested role for immune dysfunction. Autoantibodies against CNS proteins, including neuron-axon filament proteins, cerebellar neurofilaments, myelin basic protein, brain endothelial cells, caudate nucleus, and serotonin receptors have been reported in a subset of ASD patients.
There remains a need for understanding the etiology of ASD and for diagnostic tests predictive of an individual's risk for developing the symptoms indicative of an ASD, allowing for early intervention in the treatment of this neurodevelopmental disorder.